Automatic re-set mechanism for timing devices and the like



Sept. 6, 1960 F. L. RlGGlO 2,951,372

AUTOMATIC RE-SET MECHANISM FOR TIMING DEVICES AND THE LIKE Filed June 19, 1959 INVENTOR. FFEFINK L. RIGGIO gofizm/ wjaw md HTTOENE 5 AUTGMATIC RE-SET NIECHANISM FOR TllVHNG DEVICES AND THE LIKE Frank L. Riggio, Essex, Conn, assignor to Cramer Controls Corporation, 'Centerbrook, Conn, a corporation of Connecticut Filed June 19, 1959, Ser. No. 821,425

Claims. (Cl. 74-1) This invention relates to re-set mechanisms, such as those used for re-setting timing devices after a timing operation. The invention has particular reference to an improved re-set mechanism adapted to return an operating shaft of a timer, or the like, to its starting position from any position to which the shaft has rotated, without danger of becoming stalled due to the presence of the usual dead-spot in such mechanisms.

Although the reset mechanism of the present invention may be used with any device in which it is desired to return an operating shaft to a starting position, the invention will be described for illustrative purposes in connection with a timing device of the reset type.

In timers of the re-set type, the re-set mechanism, as commonly made, comprises a heart-shaped cam fixed on an operating shaft which actuates a timing pointer. A re-set member, such as a pivoted arm, carries a roller or other part adapted to be moved into engagement with the cam periphery upon actuation of the re-set member, this part being engageable with the cam periphery at the region of its low point when the shaft is in its starting position. Thus, when the shaft is rotated through a certain angle incident to a timing operation, it may be returned to its starting position by actuation of the re-set member, which urges the roller or other part against one or the other of the cam surfaces curving from the low point to the high point of the heart-shaped cam. That is, the shaft will be rotated in one direction or the other back to its starting position, depending upon which of these two cam surfaces is opposite the roller or other cam-engaging part of the re-set member when the timing operation has been completed.

With re-set mechanisms of this type, it sometimes happens that the high point of the heart-shaped cam is directly opposite the cam-engaging part of the reset member when the timing operation is completed. As a result, when the re-set member is actuated to urge the roller or other part against the cam periphery, this part is centered on the high point or dead-spot of the cam, so that the pressure of the re-set member cannot turn the operating shaft in either direction. This is attended by considerable inconvenience, of course, in overcoming the stalled condition of the mechanism.

The principal object of the present invention is to provide a re-set mechanism of simple construction which overcomes this dead-spot problem.

In a re-set mechanism made according to the invention, the reset member, during normal operation of the shaft, is in a retracted position in which its cam-engaging part is spaced from the periphery of the heart-shaped cam. The shaft is provided with a detent rotatable with the shaft and which is engageable by a finger on the re-set member to rotate the shaft upon advance of the re-set member from its retracted position by its actuating means. The detent is positioned on the shaft to be so engaged by the finger when the cam-engaging part of the re-set member is in opposed but spaced relation to thehigh point of the cam periphery. Accordingly, if the Patented Sept. 6, 1960 re-set member is actuated when the high point of the cam is opposite the cam-engaging part of the re-set member, the finger on this member will be moved into engagement with the detent on the shaft before the cam-engaging part can engage the high point of the cam, so that further advance of the reset member will rotate the shaft and the cam in one direction. Thus, the cam will be rotated by the finger and detent through a sutficient angle to bring one of the curved cam surfaces directly opposite the cam-engaging part of the re-set member by the time this part engages the cam, whereby further advance of the re-set member re-sets the operating shaft to its starting position in the usual manner.

For a better understanding of the invention, reference may be had to the accompanying drawing, in which:

Fig. 1 is a vertical sectional view, partly in side elevation, of one form of the new re-set mechanism;

Fig. 2 is a front elevational view of the mechanism shown in Fig. 1; and

Fig. 3 is a view similar to Fig. 1, showing a modified form of the mechanism.

Referring to Figs. 1 and 2, the reference numeral 10 designates an operating shaft of a timing device, or the like, the shaft being journaled in suitable bearings, one of which is shown at 11. The shaft 10 is adapted to be driven in one direction by any suitable means, such as a driving shaft .12 connected to the shaft 10 through gearing 13. It will be understood that when the operating shaft 10 is thus rotated in one direction from the driving shaft 12 and then stopped, it is desired to re-set shaft 10 to its starting position in preparation for a subsequent operation.

The re-set mechanism comprises aheart-shaped cam 15 fixed on the shaft 10, and a re-set member 16 operable on the cam to return the shaft 10 in one direction or the other to its starting position. The cam 15 has on its periphery a low point 15a and a high point 15b located, respectively, at a minimum and maximum radius from the rotation axis of shaft 10. The camperiphery also has two curved surfaces and 15d interconnecting the points 15a and 15b and each extending at a progressively increasing radius from the rotation axis as the surface curves from the low point 15a to the high point 15b.

The re-set member 16, as illustrated, is in the form of an arm having spaced ears 17 at one end for mounting the arm on a fixed pivot 18. Intermediate its ends, the arm 16 carries a roller 19 engageable with the periphery of cam v15. A flexible projection 20 on the arm is formed at its free end with a hook 21 engaged by an actuator 22. The latter is reciprocable in the vertical direction, as viewed in Figs. 1 and 2, to advance and retract the roller 19 relative to the cam 15.

In the starting position of operating shaft 10, the low point 15a of cam 15 is directly opposite the roller or cam-engaging part 19 on the reset member 16, and normally the member 16 is held by its actuator 22 in a retracted position in which the roller 19 is spaced somewhat farther from shaft 10 than is shown in Fig. 1. The shaft 10 is driven from shaft .12 in a counterclockwise direction, as viewed in Fig. 1, through a certain angle from its starting position, at which time the shaft 12 is disconnected from its power source (not shown) so as to stop the rotation of shaft 10. The re-set actuator 22 then advances the re-set arm .16 to engage roller 19 with one or the other of the curved cam surfaces 150 and 15d, depending upon the stopping position of shaft 10. Further advance of arm 16 by its actuator 22 urges roller 19 against the cam surface 150 or 15d and thereby rotates shaft 10 clockwise or counterclockwise, respectively, until roller 19 seats in the angle formed by these cam surfaces at the low point 15a, so that the shaft 10 is returned from the shaft 12 should be stopped when the high point 15b is directly opposite the roller 19, as shown in Fig. 1,, the subsequent advance of re-set arm 16 will not re-set the operating shaft 10 because the roller 19 will squarely engage the dead-spot" 15b so that it cannot rotate the operating shaft in either direction.

To avoid this dead-spot problem, a second cam 23 is fixed on shaft 10 adjacent the heart-shaped cam 15, the cam 23 carrying a peripheral detent 24. As shown in Fig. l, the periphery of cam 23 also has a cam surface 23a extending around shaft 10 from the tip of detent 24 to the base of this detent in the direction of rotation of this shaft by the driving shaft 12. Also, the re-set member16 is provided with a finger 25, the free end of which is engageable with detent 24 by advance of re-set arm 16 when the high point 15b is substantially opposite the roller 19. As shown in Fig. 1, the finger 25 is so proportioned as to effect such engagement with detent 24 while roller 19 is still spaced a substantial distance from the high point 15b.

With this construction, when the re-set arm 16 is held in its fully retracted position by the actuating means 22, the operating shaft 10 may be rotated through 360 from its starting position without causing engagement of detent 24 by the finger 25, because normally the re-set arm 16 is retracted from shaft 10 a somewhat greater distance than is shown in Fig. 1, so that the tip of detent 24 can I just clear the finger 25. However, if shaft 10 should happen to stop with the high point 15b substantially opposite the roller 19, as shown in Fig. 1, the advance of re-set arm 16 by its actuating means 22 will cause the free end of finger 25 to engage the opposing surface of detent 24 before roller 19 can engage the high point 15b. Accordingly, upon further advance of re-set arm 16 from the position shown in Fig. 1, the shaft 10 will be rotated counterclockwise by finger 25 until the roller 19 engages cam 15, at which time the roller will engage the curved cam surface 15d at a point substantially beyond the high point 15b. Thus, further advance of re-set arm 16 will cause roller 19 to move along the cam surface 15d, thereby continuing the counterclockwise rotation of shaft 10 until the latter is returned to its starting position.

The actuating means 22 for the re-set member 16 may be operated in any suitable manner. As illustrated, it is a pin projecting laterally from the plunger 27 of a solenoid 28, the plunger being urged by a spring (not shown) to a raised position inrwhich the re-set member 16 is fully retracted. Thus, upon energizing of solenoid 28, the plunger 27 is drawn downwardly to force roller 19 against the periphery of cam 15.

In the embodiment shown in Fig. 3, the re-set arm 16:: carries a finger 25a pivotally mounted on the pin 30 on which roller 19 is rotatable. A spring 31 is secured to pin 30 and has a free end engaging a projection 32 on finger 25a, so as to urge the free end of this finger against the periphery 23a of cam 23. As the operating shaft 10 is driven counterclockwise incident to the timing operation, the free end of finger 25a rides along the cam surface 23a until it passes over the tip of detent 24 and is urged by spring 32 against the cam surface 23a at the base of detent 24, at which time the high point of cam 15 is substantially opposite roller 19. Consequently, it

at this time the operating shaft 10 is disconnected from its power source and the re-set arm 16a is advanced by its actuator 22, the engagement of finger 25a with detent 24 causes shaft 10 to be rotated counterclockwise until roller 19 engages cam surface 15d at a substantial distance from the high point of cam 15, whereupon further advance of arm 16a returns shaft 10 to its starting position in the usual manner.

I claim:

1. In a device having an operating shaft mounted for rotation in opposite directions, and means for rotating the shaft in one direction from a predetermined starting position, a re-set mechanism for returning the shaft to its starting position, said mechanism comprising a heartshaped cam fixed on said shaft and having a periphery provided with high and low points located, respectively,

at a maximum and a minimum radial distance from the rotation axis of the shaft, the cam periphery also having two curved surfaces interconnecting said points and each extending at a progressively increasing radius from the axis as the surface curves from said low point to said high point, a re-set member having a part engageable with the cam periphery at the region of said low point when the shaft is in its starting position, the re-set member being normally in a retracted position in which said part is spaced from the cam during rotation of the shaft, actuating means for advancing the re-set member from its retracted position to urge said part against one of said curved surfaces and thereby rotate the shaft to its starting position, a detent rotatable with the shaft, and a finger on the re-set member engageable with the detent to rotate the shaft upon said advancing of the re-set member, the detent being positioned on the shaft to be so engaged by the finger when said part of the re-set member is in opposed but spaced relation to the high point of the cam periphery, whereby said mechanism is operable to re-set the shaft to its starting position from any position of the shaft.

'2. A device according to claim 1, in which the re-set member is an arm pivoted for swinging movement laterally of the shaft.

3. A device according to claim 1, in which the re-set member is an arm pivoted for swinging movement laterally of the shaft, said part being a roller on the arm.

4. A device according to claim 1, in which the detent is mounted on the shaft adjacent the cam, said finger being located on the re-set member at one side of said part.

5. A device according to claim 1, comprising also a second cam on the shaft adjacent the heart-shaped cam and carrying said detent, the second cam having a cam surface extending around said axis from the tip of the detent to the base of the detent in the direction of rotation of the shaft by said rotating means, the finger being pivotally mounted on the re-set arm and urged against said cam surface of the second cam.

References Cited in the file of this patent UNITED STATES PATENTS 949,705 Hummel Feb. 15, 1910 2,224,905 Franz Dec. 17, 1940 FOREIGN PATENTS 246,713 Italy Apr. 3, 1926 

